The present invention relates to a plant for producing metal powder from metal melts, the plant containing a first chamber with a device for converting a melt stream initially into liquid and then solid metal particles in a non-oxidizing atmosphere, a tundish with a closable floor opening that can be mounted on the first chamber and emptied therein, as well as a melt device for filling the tundish with metal melt.
Such metal powder plants in which the tundish is permanently mounted on the powder production chamber and in which the melt device for filling the tundish is an open induction furnace, are known in the art. However, with such plants there is the danger of a partial oxidation of the melt by atmospheric oxygen, as well as an undesirable absorption of gas by the melt (German Offenlegungsschrift No. 24 59 131).
A vacuum induction melt plant with a lock device for the finished casting or ingot casting is known from German Auslegeschrift No. 1 041 652. The molds neither have a floor opening nor do they serve for transporting the metal melt to a metal powder plant. The molds do not have a cover and must therefore be cooled in a lock chamber until the melt has at least partially solidified. The molds also cannot be termed tundishes.
A vacuum device for producing finished castings and which in principle is identical to that of German Ausleseschrift No. 1 041 652 is also known from German Auslegeschrift No. 1 182 396. The molds serve neither for transporting the melt to a further processing plant, nor do they have a suitable closure means for which the mold contents can be protected against the influence of the atmosphere during transportation.
German Auslegeschrift No. 2 007 803 discloses an atomizing apparatus which is specially intended for atomizing aluminum. The melt device is not a vacuum or protective gas chamber, and it is also not provided with a lock device. Instead, the molten aluminum is run off via an open channel into a likewise open transporting vessel which transports the melt to an atomizing apparatus in which it is atomized under a protective gas.
The prior art also includes metal powder plants in which a further gas-tight chamber containing the tundish and the melt device is arranged directly on the powder production chamber, so that a protective atmosphere can be maintained both in the region of the melt device and also in the powder production chamber (German Offenlegungsschrift No. 15 58 370 and German Offenlegungsschrift No. 23 08 061). Such metal powder plants have, however, a considerable structural height, since it has to be remembered that the chamber for producing the metal powder has itself large dimensions, governed by the falling velocity of the metal particles and by the falling velocity of the metal particles and by the necessary residence time up to the solidification of the particles. As a rule such chambers are in the form of towers or slender vertical cylinders with conical ends. Furthermore, such plants are uneconomic in operation since the melt capacity of the melt device is substantially larger than the capacity of the associated chamber for producing the metal powder.
Finally, the prior art also includes metal powder plants in which rod-shaped starting material is continuously melted and converted into droplets, which are for example atomized by means of a centrifugal disc (German Offenlegungsschrift No. 25 28 999). Such plants are preferably intended for high grade metals with extremely high purity requirements, however, they have a low efficiency due to the draining-melting process.